So, experts, the following applies

**B-body pinion measures 4 degrees up when perches are level.

**E-body pinion measures 7 degrees up when perches are level.

Im building a D60 as you know for my Cuda, it'll have around 600Hp flywheel with 727, std rear leaf springs, I have now approx 2.6* pinion down to driveshaft angle, question is, do I set the spring perches to suit a B body or an E body???, if I set them up to suit a B body I will have approx 5.6* pinion down to driveshaft, I intend to raise the back of the gearbox a little which will probably increase the pinion angle a degree further.

Greg

you'll want the pinion angle parallel to the transmission angle on ACCELERATION, you need to determine the transmission/engine driveline angle first as it sits in a loaded chassis at ride height, I would do this in car with the axle/perches bolted in place but not welded, but able to rotate, bring the pinion up to a parallel angle of the transmission/engine driveline angle, if the driveshaft is available, install and check the u joint/shaft angle in relation to the transmission/pinion, you generally want a 1-1.5 degree deflection on the U joints, no more than 3 degrees maximum deflection, then nose down the pinion 3 degrees from your parallel driveline/transmission angle (some will say 5 degrees, but I find 3 more real world), then tack weld the perches, then remove the axle housing and finish weld, invest in an inclination meter, you may have to adjust some values based on the driveline angle, shaft angles, pinion angles, ride height, etc, etc



Keep in mind with the pic below this is the ideal driveline/pinion angle UNDER ACCELERATION

The below is what my angles are now, I have to raise the rear of the trans

What Dayclona said, you want em parallel but in different planes so if the trans output shaft is 3 up then you'd want the rear ujoint 3 down plus 1 or 2 more down (4 or 5 total on the pinion) cuz it will rise on accell. the amt of EXTRA you rotate the rear down from parallel depends on the app (street/race/hauling). And as said you want the ujoint angles as minimal as possible (but not totally inline). from your diagram you'd wanna raise the trans and or the pinion (both maybe) to get what you need

Raising the trans is my first choice, Im about to install a 600HP 408 serious street with the odd trip down the 1/4. so, as its std E body at the moment with std ride height, im thinking of increasing that pinion angle to be somewhat more like a B Body angle, my trans is bothering me though, im not sure I can get the trans up physicaly more than about a 1/2", to go more I'd have to put longer studs in the trans or go bolts, still, not understanding why as a factory car it has the driveshaft angling up out of the trans, ive measured and measured again and again to verify and I'll do it again later today. I dont have any vibrations at speed or problems at present. I do want to raise the trans as it will also raise my header flanges, rear trans mount is brand new so it hasnt collapsed.

One thing to watch is what the car does under hard acceleration. Yes the pinion wraps up but the rear suspension may stand or squat depending how well it works.
If a car stands hard wouldn't that significantly change the relationship of the trans to the shaft?
I saw a while back where some of the drag guys were using a camera at the rear tire and you could see some of what the rear spring was really doing in slow motion. It's actually pretty violent.
I would be interested in seeing a shot of the same vehicle watching the pinion angle change as the traction increases and then decreases to better understand what it does to the pinion angle in reality.
Good luck...

yeah, I know what your saying, driveline angles shoudl be pretty simple and technically they are, but this is doing my peabrain head in!!!

You want to set it as Dayclona said. Bottom line you want the trans/eng centerline parallel to the pinion centerline on acell. Right now if you can get the eng/trans to zero you would be pretty close with the pinion at 2.3 down right now. I usually set my leaf spring street cars with the pinion about 3 down with the car at rest so it should be close to zero on acell if the eng/trans is at zero. If you cant get the eng/trans to zero get it as close as you can. If say you get the eng/trans at 1 down then set the pinion at 2 down so it will be at 1 up on the gas with the eng/trans at 1 down so it will have parallel centerlines. Ron

Thanks guys, Ok, I’ve just spent a couple of hours measuring and measuring and measuring to verify what I’m getting. Right now as it sits, its a standard 1973, Cuda, 340/727, 8.75. factory springs with poly bushes, I have 26.5" high tires on it and the rear fender lips are 25.25" off the ground so I wouldn’t say its lowered as such or even sagged all that much over the years, not significant enough to give me the angles im getting.
anyway. I started at the engine and zero'd my digital angle finder (used an engineers square on the harmonic balancer, then also checked it on the top of the trans lug they have machined surfaces parallel to the centreline, then also on the bottom of the rear trans mount, all gave me zero so good to go) I then attached it to the driveshaft, the driveshaft is at 2.6* up from the eng/trans centreline. I then moved to the rear, zero'd on the driveshaft and checked the pinion angle, it is at 2.5* nose down to the tailshaft, like I have in the image above.
I loosened the two bolts holding the trans mount to the trans and jacked it up approx 3/8" and only took .7* out of the eng/trans to driveshaft angle so its looking like I will need to jack the rear of the trans up prob 3/4" at least to get that line anywhere close to zero!!!! this will also increase my pinion angle to, I'm guessing something like 4*??

So I have two dilemma’s, the first is the existing driveline angle particularly the eng/trans angle and how to resolve it,
The second is, setting the perches up on the Dana, yes I can put it in place without them welded , set the angle and tack them but that is problematic for other reasons right now. As it stands, with the angles I have I’m pretty much going to set it up per a normal E Body (7 degrees up when perches are level.) as I feel the B Body pinion down an extra 3 deg might be too much.

I would decide if you want to weld the perchs to the OE specs (B? E?) then use the shims to correct it OR if you want to get the Dana matched to what you have now & permanently weld the perchs at that angle. I agree this angle stuff appears kindergarten level simple but is confusing and keep in mind that you are finding/correcting the angle of the trans CL and pinion CL not the driveshaft angle tho you need the shaft angle to do the simple math to find those two angles (front trans/rear pinion) up or down from the shaft and get em fairly close to zero and very close to each other (but opposite, one negative one positive) then add in some more pinion downward angle for your particular app. EDIT the shaft is always (for our purposes) considered to be at zero then the trans and pinion are up or down from that zero baseline

Leave it alone. Here is why. In order to get the trans/driveshaft angle 2 to 3 deg the opposite way you will need to move the tailshaft up more than the floor will allow.

The advice of parallel angles of the eng/trans to pinion are good but MATCHING is the real answer and yours is matching.
A driveshaft slows down and speeds up twice for each revolution. Matching the 2 angles is the best way to combat the issue and parallel and opposite both accomplish that.

I'm totally against bigger pinion angles. Numbers of 5-7 are talked about in the Mopar Chassis manuals and many members here to this day follow this advice. Great on a weak sprung leaf spring car but big numbers like that will vibrate the car. I'm more from the 2 deg pinion down school and if you need more than that to compensate for axle wind up, chase that problem and control axle wind up.

In most cases with stock body cars the pinion is lower then the trans is. If you leave what you have the pinion is going to go up to around 0 to 1 degree up when on the gas which with the trans at 2.3 down will not be very good and you may not get away with it as you would know if it has to much driveline vibration.
Myself I would try to get the trans to 0 degrees is you have enough room. And with the pinion at 2.3 down when on the gas it should be around 0 to 1 degree since its a leaf spring car as I would be happy with that. But I dont know if you have enough room to raise the trans but if you do I feel thats the easiest way to set it with the least amount of work.
Raising the trans should not change the diff pinion angle but of course I would recheck it and make sure where it is after raising the trans if you can raise the trans. If you cant get the trans to 0 then see how close you can get it and work from there. Ron

What motor mounts are you using?

Whats your sump to cross member clearance?

If you have room, dropping the motor a little may help

In an ideal world, the motor should be flat when the car is in in motion not sitting still.

engine mounts are original, bottom of pan is barely above the bottom of the K member, new trans mount of original design and size, motor is sitting in the engine bay pretty much level when car is on all four, nothing looks crazy, I dont want to lower it any more as Im using a big pan on the 408 when it goes in, as previously indicated, at any speed through to 100 mph, I dont get any driveline vibration so it cant be that out of the ordinary, I just figured the driveshaft should angle down from the trans, not up like in my case, if anyone else has an E body, id be interested to know about theirs, as for the setting up my Dana, i'm goint to set it up the same as what I have now which is E body angles.